1. Field of the Invention
This invention relates to a system for fitting mounted rollers which allows for quick release/re-fitting of the rollers and more particularly though not solely to a quick release roller mechanism for use in a stretch head of a stretch film wrapping machine incorporating driven rollers.
2. Brief Description of the Prior Art
Apparatus which include rollers having an axis of rotation wherein the roller is supported at either end often require the roller to be removed for re-fitting or servicing and/or subsequent replacement. Some apparatus including rollers as described above include driving means for rotating the roller, complicating the removal and re-fitting process significantly.
An example of apparatus having driven rollers which are often required to be removed and re-fitted is a stretch wrapping head for a stretch wrapping film used in the packaging of products, often on pallets, wherein the stretch wrapping head is rotated about the goods on the pallet and moved in a vertical direction so that the goods on the pallet are held in position and protected from the environment by the stretched wrap. An example of such a stretch wrap head is disclosed in EP-B-747287 and an alternative apparatus which includes a similar type of stretch head is disclosed in EP-A-803437 in which the stretch wrap head is suspended from a rotating arm which rotates above the object to be wrapped.
The stretch heads disclosed in the above mentioned patent specifications both include two driven rollers, the surface speeds of which are not the same and through which a continuous length of plastics film is passed and stretched by the difference in speed between the surface of the rollers. EP-A-919467 discloses an improved stretch wrapping head which includes two parallel driven rollers but which also includes at one end of the rollers an opening to allow easier access to wind the film on the rollers prior to commencing operation.
In each of the above mentioned stretch wrap heads, replacement or removal of the rollers is time consuming and requires the use of tools. It would be an advantage if the rollers could be quickly and simply removed to allow for maintenance and or re-fitting.
Accordingly, it is an object of this invention to provide a quick release mechanism for a roller which at least goes some way towards overcoming the above disadvantages.
According to this invention, a quick release mechanism for a roller comprising:
frame means in which the roller is adapted to be mounted in use;
apertures in either end of the roller, the apertures aligned with the axis of rotation of the roller; and
stub axle means which connect either end of the roller to the frame means by passing through respective holes aligned in the frame means and into the respective roller apertures, the connection between the roller and each stub axle means allowing substantially free angular rotation of the roller relative to the frame means;
wherein one of the stub axle means is axially fixed in the frame means and driven rotationally and provided at or near its end with a non-circular cross-section, the cross-section of the roller aperture into which the driven stub axle means fits having a corresponding shape to allow the roller to be rotated by the driven stub axle means; and
wherein the other stub axle means is releasable from its connection with the roller aperture and its connection with the frame means solely by movement along the axis of rotation of the roller, away from the roller, the removable stub axle means having a cylindrical shaft which is adapted at one end to pass through the hole in the frame means and to fit within the aperture in the roller and provided at its opposite end with a knob to facilitate removal of the removable stub axle means from the roller aperture and frame means, the cylindrical shaft including at least two axially separated detents to allow the removable stub axle to be selectively positioned either engaged with the roller and frame means or disengaged from the roller but still engaged with the frame means to facilitate removal of the roller from the frame means.
According to a second aspect of the present invention, a stretch wrapping head for a stretch wrapping machine is adapted to pre-stretch a plastics film through stretch rollers supported in a frame, the rollers held in the frame by a quick release mechanism according to the above paragraph.